It has been recognized that forwardly facing walls of trailer vehicles which extend above the roof of the towing vehicle are susceptible of creating substantial drag forces which can impede the forward progress of the vehicles. Such drag forces can be reduced by anchoring an air-deflecting shield on the roof of the tow vehicle to cause relative air currents to be deflected laterally and upwardly so as not to impinge as directly on the towed vehicle as they would in the absence of such a deflector. The deflection of air currents by such shields not only reduces the consumption of fuel during towing, but also can improve stability of the towed vehicle as well as reduce wind created noise around the towed vehicle.
Typically house trailers drawn by automobiles or pick-up trucks extend several feet higher than the roof of the tow vehicle. This is particularly true of the fifth wheel type of trailers towed by pickup trucks because of the increased load towing abilities for such a configuration.
House trailers are usually provided with kitchen and lavatory facilities which require a substantial quantity of stored fresh water during periods of self-contained operation. Waste water during such operation drains to holding tanks in the trailer. Although the size of holding tanks is correlated to the size of fresh water tanks, it is often desirable to have extra capacity for fresh water, especially when water can be used without the necessity of having to temporarily dispose of waste water in holding tanks for subsequent disposal in a sewer or special dump site.